2023 Enhanced Predatory Fish Removal and Relocation Study
The Enhanced Predatory Fish Removal and Relocation Study (EPFRRS) was implemented from March 2021 through June 2023. The EPFRRS was included in the proposed action for the 2019 state and federal endangered species consultation for the long-term operations of the Central Valley Project and State Water Project. The goal of the EPFRRS was to use the most successful methods from previous predator relocation studies conducted by the Department of Water Resources (DWR) from 2016 to 2020, including the Predator Reduction Electrofishing Study (PRES) and the Predatory Fish Relocation Study (PFRS), to reduce predation mortality on protected fish species in Clifton Court Forebay (CCF), primarily juvenile Chinook Salmon and steelhead. In 2023, predator collection and relocation were conducted from January 3 through June 1. Cancellations occurred during inclement weather conditions that made sampling unsafe (e.g., high winds or rain). There were three gear types used during the 2023 effort: electrofishing, beach seining, and hoop trapping. Electrofishing consisted of two to three electrofishing boats focusing on hotspots identified during the PRES and during the 2021 and 2022 EPFRRS efforts. Hoop traps were deployed for 24-48 hours of passive fishing, when possible, given SWP operations. When hoop traps could not be fished and an additional electrofishing boat was available, the third electrofishing boat was fished instead. Predatory fish removed included black basses, Striped Bass, catfish, and sunfish. However, sunfish were removed opportunistically and were not specifically fished for. Fieldwork was scheduled for four days a week each week. In total, predator relocation was conducted on 48 days during the 2023 field season, which is more than the 2021 field season (26.5 days) which was impacted by the COVID-19 pandemic. However, despite the field season being shorter by nearly a month, the 2022 field season had more days the field (55 days), primarily due to weather conditions.
Data files
Supporting files
| Data title and description | Access data | File details | Last updated |
|---|---|---|---|
EPFRRS 2023 Final Report This report summarizes and compares all 3 years of EPFRRS. A total of 57,864 predatory fish, or approximately 22,779 kg (50,115 lbs.) of calculated biomass, were removed during the three years of the EPFRRS. Hoop traps caught the most predatory fish, with nearly half of the total catch, consisting primarily of catfish. The beach seine caught the second most, with the majority being Striped Bass, followed by the electrofishing. Electrofishing was the most successful gear type for black bass across all years. The beach seine caught more sunfish than either e-fishing or hoop traps across the study (892, 620, and 254, respectively). Mortality rates were low, with approximately 0.03% total for the study. | PDF | 06/24/26 |